1. Field of the Invention
The present invention relates to an inflatable insulation module that is breathable, i.e. permits the passage of moisture vapor. This inventive module can be incorporated in a wide variety of garments such as suits, vests, jackets, trousers, hats, gloves, socks, and boots. It can also be used in sleeping bags and bedcovers. The inventive module allows the wearer to adjust the amount of insulation being provided depending on the environmental conditions experienced or the activities that the wearer is engaging in. The inventive module is also provided with a relief valve means for reducing pressure in the inflated portion should the module be subjected to sudden or excessive stress.
2. Background of the Invention
Inflatable garments are well known in the art. The concept of using an air impermeable water vapor permeable material to form the inflatable portion of an insulating module is also known. U.K. Patent Publication 2,317,102 A describes such a module. The air impermeable, water vapor permeable material taught in that publication is an unsupported elastic material such as a polyurethane. The material must be sufficiently elastic to compensate for the stresses arising as a result of inflation, flexing or impact. In order to have sufficient strength, the material has to have a minimum thickness of 50 microns and is preferably 100-150μ thick. As a result of using relatively thick membranes, the breathability of the module is acknowledged to be reduced. In some embodiments, both sides of the inflatable cavity are formed from such relatively thick membranes that it further reduces breathability.
U.K. Patent No. Application GB2,323,015A describes a variable thermal insulation material with an inflatable layer created from an envelope of breathable material formed from a laminate arrangement of hydrophilic films that are bonded to microporous substrates. This document prefers the combination of microporous and hydrophilic material sold under the trademark GORE-TEX by W. L. Gore & Associates, Inc. The composite article is arranged so that the inflatable cavity is created by hermetically sealing the hydrophilic materials to each other with the microporous substrate on the outside of the hydrophilic film.
While the invention described in U.K. Patent Application 2,323,015A provides many of the advantages of the present invention in practice, garments have tended to leak or rupture when subject to external stresses such as impact. Improvements to overcome these deficiencies in the prior art are contemplated.
These and other purposes of the present invention will become evident from review of the following specification.